What exactly is the giver going to give to jonas? why do you think he has this in the first place, and what does he do with it

The giver is transmitting memories to Jonas. The Giver is giving Jonas a memory of strong pain so that he can bear some of the Giver's pain for him.

Sometimes when you read things in your head, you skip overall small details/words. when you read aloud, you hear those words and it’s easier to comprehend what you just read. saying things aloud also you remember them.